Ten years ago, as more and more superpowered mutants emerged, a powerful telepath by the name of Charles Xavier had a vision of peace between humans and mutants. To that end, he gathered five mutants to form a team of defenders: the First Class of his X-Men. The X-Men protected humankind by battling their evil, cruel counterparts, though rarely were they recognized for their achievements. That is, until the entire world came under attack by the apocalyptic swarm of Galactus, the World-Eater. Superheroes and supervillains, teams and loners, military and vigilantes—all pitched in for the defense of Earth.

They won, but it cost them dearly.

By the time the dust settled, many beloved heroes were dead, and many others faded away due to grief or fear. The only team left standing was the X-Men. Recognizing that the world needed heroes badly, they moved to Manhattan, opened up a skyscraper school, and buffered their ranks with students from Emma Frost's Massachusetts Academy, as well as anyone with the stamina and the will to be a hero—even humans.

Now, it's been three years since Galactus, and they're still the only game in town. In a city as corrupt as New York, being the sole force for good doesn't necessarily bode well...